No reads on UTG - what should I be doing in this situation? Should I be taking the free card or should I betting here to try and take the pot down /build the pot?

I would really also appreciate an explanation of why we should play this in a certain way.

PokerStars No-Limit Hold'em, $0.05 BB (6 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

UTG ($4.13)
MP ($8.03)
CO ($0.62)
Hero (Button) ($9.18)
SB ($9.95)
BB ($17.69)

Preflop: Hero is Button with J, K
UTG calls $0.05, 1 fold, CO calls $0.05, Hero raises to $0.30, 2 folds, UTG calls $0.25, CO raises to $0.57, Hero calls $0.27, UTG calls $0.27

Flop: ($1.78) 3, 3, 10 (3 players)
UTG checks, CO bets $0.05 (All-In), [color=#CC3333]Hero ???